The Imperial Rite of the Amarr Empire emphasizes loyalty to the Imperial Throne as an essential element of the Amarr faith. To Amarr's holy warriors wavering in loyalty is not merely cowardice or turpitude, rather it is a mortal sin that leads to damnation if not expunged through battle in service of Holy Amarr.
The Imperial armed forces are huge and remarkably diverse, made up of many branches and including contingents drawn from all across the immense domains of the Amarr Empire. The unity of such a vast military is found in the Amarr faith and its allegiance to the Imperial Throne. These pants are part of a set of clothes that declares your loyalty to the Emperor and displays your willingness to take up arms in defense of Holy Amarr.